1. Field of the Invention
The present invention relates to an image display apparatus, and, more particularly, to a chained image display apparatus having a mutual examining function by which a plurality of image display apparatuses, controlled by a central control unit and connected with one another in series, recognize any interruption of power supply to one of the plurality of image display apparatuses and inform the central control unit of the power supply interruption.
2. Description of the Related Art
FIG. 1 is a block diagram showing a conventional chained image display apparatus. A first image display apparatus 100, a second image display apparatus 101, and an nth image display apparatus 103 are each configured to have a portion receiving a control signal and a buffer transmitting the received control signal to a next image display apparatus.
The conventional chained display image display apparatus is disclosed in U.S. Pat. No. 6,137,490.
The second image display apparatus 101 inputs and outputs a control signal through an input port 101-1 and an output port 101-2. A control signal driving unit 101-3 converts the control signal inputted through the input port 101-1 into a signal having a level that can be recognized by the second image display apparatus 101, and outputs the signal to a control unit 101-4. Then, the control signal driving unit 101-3 converts the signal output from the control unit 101-4 into a signal having a level that can be recognized by a next image display apparatus, e.g., a third image display apparatus (not shown), and outputs the signal to the third image display apparatus (not shown) through the output port 101-2.
In a conventional chained image display apparatus comprising a plurality of image display apparatuses connected with one another in series, if power supply of an image display apparatus, e.g., the second image display apparatus 101, is interrupted, the image display apparatuses following the image display apparatus, e.g., the third image display apparatus through the nth image display apparatus, can not be controlled by the central control unit. This is because a control signal output from the central control unit is sequentially transmitted through a previous image display apparatus, e.g., the first image display apparatus 100, to the next image display apparatus, e.g., the second image display apparatus 101. On the other hand, if the image display apparatuses are connected in parallel, only a limited number of image display apparatuses can be connected to the central control unit, thus the number of image display apparatuses connected to the central control unit cannot be increased.